build-load release v0.3.0

Reworked the command line flags in order to improve the convenience and the number of required flags. The output registry flags use shorter names now. Furthermore, the hostname and org/namespace flags are combined into one flag. Also, the strategy flag was removed and additional logic added to correctly guess the strategy based on the provided cluster build strategy flag input.

The test plan YAML uses the shipwright-io/build internal BuildSpec instead of an own configuration to be more aligned with the shipwright project.